So I got a 84 Z28 carbed manual transmission. So on early morning I let my engine warm up(obviously) but when I drove my car for about 40 min and got off the freeway and back on th ethe regular streets I notissed that my car went form idling from 500RPM to about 1500RPM's!??? IDK oif this is normal or what I also put a pikture so that you could see where exactly my RPM gauge is at...

 

Check for vacuum leaks, tighten up the 4 carb hold down bolts.
When its idling high, look at the carb linkage, maybe it hanging up. Or its on the fast idle cam.

 

Ok thanks ima check it out...but is there anything else that might cause it???thanks!


and do you know why exactly this happens???